With whom was the covenant of grace made? The covenant of grace was made with Christ as the second Adam, and in him with all the elect as his seed. In baptism God proffers to our children the truth and promise of the gospel - a truth which is accomplished through the work of Christ and applied by the Spirit, according to God's election and his enabling us to respond in faith. "If you belong to Christ, then you are Abraham's seed, and heirs according to the promise" (Gal. 3:29 NIV).
Source: New Horizons, 2005. 3 pages.